The present invention relates to a pivoting door thrust reverser for a turbojet engine, more particularly to such a thrust reverser having a panel slidably mounted on the pivoting thrust reverser door.
Turbofan-type turbojet engines are well known in the art and typically comprise a fan at the front of the turbojet engine which directs a flow of bypass air through a duct bounded on the inside by the engine cowling and on the outside by a fan cowling. The generally annular duct bounded by the engine cowling and the fan cowling may channel both the bypass flow and the primary exhaust gas flow at a downstream portion or may channel only the bypass flow.
In aircraft on which the turbojet engine is mounted outside of the airframe structure, the fan cowling and the engine cowling are configured to form boundaries of the bypass flow duct and to provide aerodynamic outer surfaces to reduce drag.
FIGS. 1 and 2 illustrate a known pivoting door-type thrust reverser associated with the fan cowling of a turbofan-type turbojet engine. As illustrated in FIG. 1, an upstream portion of the fan cowling 1 which defines the outer limits of the bypass flow duct is generally concentrically arranged about the turbojet engine (not shown) and generally comprises an external cowling panel and an internal cowling panel interconnected by a frame 6. The outer surface of the external cowling panel has an aerodynamic surface over which the air external to the engine passes during aircraft flight. The inner surface of the inner cowling panel defines the outer boundary of the bypass flow duct 15 through which the bypass flow air passes.
The fan cowling also comprises a thrust reverser, illustrated generally at 2, and a downstream fairing 3. The thrust reverser 2 comprises a door 7 pivotally attached to the cowling 1 such that it is movable between a closed, forward thrust position, illustrated in FIG. 1, and an open, reverse thrust position in which the upstream end (towards the left as viewed in FIG. 1) of the thrust reverser door 7 is moved outwardly from the cowling, while a downstream portion is moved inwardly into the bypass flow duct 15 so as to redirect at least a portion of the bypass flow through an opening in the fan cowling in a direction that has a reverse thrust component.
An actuator 8 for moving the door 7 between its forward thrust and reverse thrust positions may comprise a hydraulic cylinder mounted to the frame 6, and having an extendible and retractable piston rod connected to the thrust reverser door 7.
The thrust reverser door 7 has an outer door panel 9 and an inner door panel 11 joined together by an internal structure. The upstream end of the door 7 may have a deflector 13 to maximize the efficiency of the thrust reverser when the door 7 is in the reverse thrust position. When the door is in the forward thrust position, as illustrated in FIG. 1, the outer door panel 9 is substantially flush with the external surfaces of the upstream panel and the downstream fairing 3.
As illustrated in FIG. 2, a plurality of thrust reverser doors 7 may be incorporated into the fan cowling, such doors being circumferentially spaced around the periphery of the fan cowling. A portion 18 of the fan cowling extends from an upstream portion 4 of the cowling axially between adjacent thrust reverser doors 7 to provide structural rigidity to the fan cowling and to provide pivot mounting points for attaching the doors 7 to the fan cowling. French Patents 1,482,538 and 2,030,034 illustrate typical, known thrust reversers.
U.S. Pat. No. 3,605,411 discloses a pivoting door-type thrust reverser in which the deflector mounted on the upstream or forward end of the thrust reverser door is movable to an extended position when the door is in the reverse thrust position.
French Patent 2,618,853 discloses a thrust reverser in which the deflector is retracted when the door is in its forward thrust position to optimize engine performance.
In some applications, as illustrated in FIG. 1, the deflector 13 projects from the inner panel 11 of the thrust reverser door 7 even when the door is in its forward thrust position without extending into the bypass flow duct. This forms a cavity 16 facing inwardly into the bypass flow duct which will slightly degrade engine performance.
French Patent 2,680,547 discloses a thrust reverser having a combination of spoilers and deflectors to attempt to optimize the direction of exhaust flow.
French Patent 1,482,538 also discloses the use of a linear actuator affixed to the stationary upstream portion of the cowling and to the pivoting thrust reverser door at a point in an upstream portion of the door.
As noted previously, the presence of the cavity 16 when the thrust reverser door 2 in its forward thrust position will create disturbances in the gases flowing through the duct 15 and thereby degrade engine performance in the forward thrust mode.